1. Technical Field
The present disclosure relates to light sources, particularly, to a planar light source apparatus which includes a number of lighting elements therein.
2. Description of Related Art
It is known that a number of lighting elements, such as cold cathode fluorescent lamps or light emitting diodes, put in an array, can form a planar light source apparatus. Assuming that a light intensity of a light-receiving position which is spaced apart a light element with a distance D is 1 unit intensity, an overall light intensity (i.e., a light intensity of the entire planar light source apparatus which includes a number of lighting elements) of the planar light source apparatus can be more than 1 unit intensity with the same distance D.
However, light intensity measured at various light-receiving positions directly in the path of light from the planar light source apparatus can vary depending on if the light-receiving position is nearer to the central region of the planar light source apparatus or nearer to peripheral regions of the planar light source apparatus. Generally, in a light-receiving position where is nearer to a central region of the planar light source apparatus, an overall light intensity can be 1.6 unit intensity, whereas in a position where is nearer to a peripheral region of the planar light source apparatus, an overall light intensity is only 1.35 unit intensity. In this regard, if a light intensity more than 1.35 unit intensity is required, the positions where are nearer to peripheral regions of the planar light source apparatus have to be abandoned.
Increasing the density of lighting elements at the peripheral regions of the planar light source apparatus has been proposed to solve the problem above, but that becomes costly in parts needed and high power consumed.
What is needed, therefore, is a new planar light source apparatus, which can overcome the above shortcomings.